The present invention relates generally to fuel additive compositions. More particularly, the present invention is directed to fuel additive compositions comprising a fuel additive component and a sustained release component for use in fuel systems, for example, engine fuel systems, such as those of automobiles, trucks, heavy equipment and the like, and fuel delivering and dispensing systems.
Fuel can entrain a wide variety of contaminants from different sources. For example, fuel frequently oxidizes and forms resinous materials such as varnishes commonly referred to as asphaltenes. Also, microorganisms such as bacteria and fungi can grow in fuel. These contaminants degrade the performance of the engine and other downstream components if left within the fuel.
Fuel filters are necessary components used to protect engines by filtering out contaminants. Generally, fuel is filtered as it enters and fills the filter assembly so that the entire filter component is doused with fuel as the fuel passes through the filter component and exits the filter assembly to travel to the engine and other downstream components such as valves, fuel lines, fuel injectors and related components. Additionally, with the advent of electronically controlled fuel injection engine systems, fuel filter systems are playing an ever increasingly important role in reducing and eliminating contaminants in fuel. Such fuel injection systems utilize high injection pressures and are sensitive to various contaminants. For example, due to the high injection pressures of fuel injection systems, minute quantities of contaminants in fuel will damage the injectors, causing galling and erosion of spray holes and tips.
Although the use of a fuel filter assembly helps eliminate contaminants from fuel, the filtering process gives rise to other problems. For example, one major problem is that the filtered contaminants, for example asphaltenes or varnishes, plug the fuel filter component as it is being filtered out from fuel. Such plugging can restrict fuel flow. Restricted fuel flow further degrades the performance of the engine, and if unattended, could lead to continued degradation of performance as well as mechanical and structural failure of the engine""s components.
Furthermore, the plugged filter can create a pressure differential in the filter assembly. Pressure differential increases as pressure increases on the unfiltered side of the filter component to force the fuel through. This can lead to contaminants being forced through the filter component, tearing and damaging the filter component.
Therefore, to maintain engine performance and reliability, the fuel filters must be replaced often, frequently as often as every 2,000 to 4,000 vehicle miles. For many vehicles, particularly commercial trucks that travel thousands of miles a month, this significantly increases vehicle maintenance and operating costs. Furthermore, other related issues become predominant with increase filter replacements, such as environmental considerations.
Fortunately, the formation of contaminants that are clogging the filter can be prevented by additives placed in fuel. For example, dispersants can be added to fuel to prevent and dissolve varnishes. However, it is difficult to maintain a constant or desired level of an additive in the fuel. Therefore, additives are typically added to the fuel tank with each fill up. However, this technique of maintaining additives in fuel is inconvenient and inefficient. For example, the additive may not be readily available or the operator may forget to add the additive. Furthermore, when the additive is added to the fuel tank, it does not always form a homogeneous mixture with fuel, which may create engine combustion problems.
Several attempts have been made to provide a fuel filter that not only filters fuel but also can provide a steady, sustained source of fuel additives. Recently, Davis in U.S. Pat. No. 5,372,942 disclosed a pressurized fuel filter having a soluble composition comprising an additive component embedded in a sustained release component, for example wax, the content of which is incorporated in its entirety herein by reference. The wax/additive composition, when contacted by fuel, slowly completely dissolves and releases additives into fuel over a period of time.
Although the device disclosed by Davis allows for slow, sustained release of additives into fuel, there are inherent problems associated with such device and the like. For example, the sustained release component, for example wax, dissolves into the fuel as it releases the additives therein. The dissolved wax may compromise the burn rate of fuel and affect engine performance. Additionally, the soluble wax may accumulate and clog the filter during cold weather operation.
There continues to be a need for an additive composition that is capable of providing a slow sustained release of additive.
New apparatus and methods for providing release, preferably sustained release, of at least one additive into a fuel, for example, a liquid fuel, have been discovered. The present invention provides fuel additive compositions that, when in contact with fuel, effectively provide for sustained release of a fuel additive into the fuel. The invention also provides an additive assembly that is adapted to be installed along a fuel line of an engine to substantially control the release rate of an additive into fuel passing through the fuel line. The present apparatus and methods are very useful and effective for use in fuel systems, for example, engine fuel systems, such as those of automobiles, trucks, heavy equipment and the like, and fuel delivering and dispensing systems.
The fuel additive compositions, in accordance with the invention, generally comprise a sustained release component and an additive component, wherein the additive component is effective to provide one or more benefits to a fuel, including, but not limited to, a liquid, for example, a hydrocarbon based, fuel, when the additive is released or dissolved into and is present in the fuel. The sustained release component preferably is a polymeric material that is substantially insoluble in the fuel, and is effective to reduce the rate of release of the additive component into the fuel.
In one particularly advantageous embodiment, the sustained release component is in the form of a matrix material, preferably comprising a polymeric material. The matrix material may be, and preferably is, initially a solid. Upon exposure of the fuel additive composition to fuel, for example, at an operating temperature of an engine, the initially solid matrix material may soften. Alternatively, the matrix material may initially be in the form of a gel or a paste. In any event, when exposed to fuel, the fuel additive compositions gradually release the soluble fuel additive or additives from within the matrix material.
A fuel additive assembly of the present invention generally comprises a housing which can be installed along a fuel line. Components of the housing preferably are made of materials which are substantially insoluble in a fuel or fuel composition even at the elevated temperatures of such fuel or composition in a working environment, e.g., an internal combustion engine, so that these components remain intact and do not dissolve into and/or otherwise detrimentally affect the fuel system. In addition, the insoluble components of the present apparatus can be reused after release of the fuel additive contained therein. The present apparatus is easy and straightforward to manufacture cost effectively.
The fuel additive assemblies of the invention are designed for use in fuel systems, such as those associated with vehicles and systems for delivering and/or dispensing fuels and the like systems, which are designed to provide sustained or gradual, preferably substantially controlled, release of at least one additive(s) into a fuel.
In one embodiment, the fuel additive assemblies of the invention comprise a housing defining a chamber including a fuel additive composition in accordance with the present invention contained therein. The additive assembly is adapted to be placed xe2x80x9cin-linexe2x80x9d at a suitable location along a fuel line. Fuel flowing in the line passes through the assembly and a portion of the fuel additive or additives is released into the fuel.
The fuel additive compositions are preferably in particle or pellet form. In one embodiment of the invention, the fuel additive compositions are in the form of pellets coated with a sustained release material.
In another aspect of the invention, a fuel filter element is provided within the assembly. Fuel entering the assembly will first become filtered of debris and particles before passing though the additive compositions disposed within the housing. Alternatively or additionally, a second filter element may be provided for filtering the fuel after the fuel has passed the additive composition.
In still a further aspect, the invention is directed to methods for releasing an additive component at a sustained, preferably substantially controlled, rate into a fuel, for example, a liquid fuel. The present methods comprise, for example, placing a fuel additive composition of the present invention in, for example, a container or cartridge, preferably made of fuel insoluble materials, in contact with a fuel. Sustained, preferably substantially controlled, release of additives into the fuel is thereby obtained.
Commonly assigned U.S. Patent Applications Serial Nos. (Attorney Docket No. D-2912) and (Attorney Docket No. D-2959CIP), filed on even date herewith, are directed to somewhat related subject matter. The disclosure of each of these co-pending U.S. applications is incorporated in its entirety herein by reference.
Each and every feature described herein, and each and every combination of two or more of such features, is included within the scope of the present invention provided that the features included in such a combination are not mutually inconsistent.
Additional aspects and advantages of the present invention are set forth in the following description and claims, particularly when considered in conjunction with the accompanying drawings in which like parts bear like reference numerals.